Rotary high-current switch



May 2l, 1968 E. E. KUssMAUl.

ROTARY HIGH-CURRENT SWITCH 5 Sheets-Sheet l Filed April 6, 1966 "ROTARYHIGH-'CURRENT SWITCH 5 Sheets-Sheet 2 Filed April 6, 1966 r (D ID @gigATTORNEYS May 21, 1968 E. E. KUssMAUL 3,384,726

ROTARY HIGH- CURRENT SWITCH Filed April 6, 1966 5 Sheets-Sheet 3ATTORNEYS United States Patent O 3,384,726 ROTARY HIGH-CURRENT SWITCHEdwin E. Kussmaul, Westwood, Mass., assignor to Kelek Company, Norwood,Mass., a corporation of Massachusetts Filed Apr. 6, 1966, Ser. No.540,568 9 Claims. (Cl. 200-155) ABSTRACT OF THE DISCLOSURE A rotaryhigh-current switch comprises a horsing with plural sub-frames withinwhich a rotor has plural longitudinally displaced sections, each sectionincluding a part of each of a plurality of mutually insulatedconductors. Alternate orientations of the housing sub-frames permitalternate access directions for bus connections to independently mountedbridging type contacts. Current interruption or reversal is effected byconnections wholly internal to the housing with minimal movement andwithin a minimal space.

The present invention relates generally to high current switches, forexample switches that may carry up to several tens of thousands ofamperes, and more particularly to switches adapted for reversing ortransfer of current connections.

In switch applications such as electro-plating it is common to usebridging-type contacts, such contacts being adapted on closing to bridgebetween the terminals or buses, being held in contact with the latter byspring pressure. Ordinarily a substantial number of such contacts arearranged in a row, and each contact is self-aligning, full-floating andindependently mounted so that an even distribution of current load canbe obtained even after the contacts have become worn or pitted in use.The preference for bridging-type contacts over the conventionalknife-type switch results largely from the smaller space required forthe switch and its operating parts.

The bridging-type contact switches hitherto available have hadshortcomings in certain applications such as reversing switches. Thestructural arrangements of bridging-type contact switches are such thatthey are basically of the single pole, single throw type. The reversingfunction for a direct current circuit or a single phase alternatingcurrent circuit requires four such switches with suitableinterconnection-s, such interconnections all being external to andbetween the switches. Thus the cost of construction and the spacerequired for connecting reversing switches of this type may beconsiderable, particularly when large currents are to be carried.

It is a principal object of this invention to provide an improvedbridging-type contact switch that is capable of reversing one or morecurrent connections with a minimum space requirement and a maximumeconomy of material, while at the same time providing lall of the knownadvantages of this type of switch.

A second and related object is to provide a switch that accomplishescurrent reversal by means wholly internal to the switch structure.

Another object is to Iprovide a switch using a minimum of space, yetbeing Well adapted for immersion in oil or other cooling iluid todissipate the heat generated by contact resistance.

Another object is to provide a switch that is so constructed that theload upon its rotary elements is balanced under all conditions, therebyinsuring uniform wear and ease of operation either manually orautomatically.

Another object is to provide a switch that can accomplish the reversingfunction with a minimum of mechanical movement of the parts.

3,384,726 Patented May 2l., 1968 ICC Still another object is to providea switch design that is flexible in regard to the possible orientationsof the input and output bus bars.

Having in view the foregoing and other objects hereinafter appearing,the features of this invention include a novel rotary switch having arotor supported within a housing and including two coaxial,longitudinally displaced sections, these sections each including twoconductors and being respectively adapted for electrical connection tothe input and output bus bars. Each section of the rotor includes onepart of each electrical conductor. Bridging-type contacts resilientlyand continuously bear upon the input and output bus bars and theelectrical conductors of the rotor, but the contacts are not providedwith the usual prior art mechanism for moving them into and out of suchcontact. Instead of moving the contacts, the present inventioncontemplates simply rotating the rotor through a given angle which canbe arranged either for current breaking or for current reversal orswitching, as desired.

Another feature of the invention is that the design of the rotor can beadapted for any desired direction of access for the input and output busbars. It is only necessary to provide the desired angular displacementbetween the parts of each conductor in the two sections of the rotor.

Other features of the invention reside in certain details ofconstruction and in modes of operation which will become evident from astudy of the embodiments hereinafter described with reference to theappended drawing, in which FIG. l is a side elevation of a preferredembodiment adapted for a rightangle displacement between the input andoutput bus pairs;

FIG. 2 is an elevation in section taken on line 2 2 of FIG. l;

FG. 3 is a simplified View illustrating the bus connections to theembodiment of FIGS. 1 and 2;

FIG. 4 is a View in perspective of an alternative form of the rotor; and

FIG. 5 is a simplified view showing the bus connections used with therotor of FIG. 4. f

Referring to FIGS, l, 2 and 3, the preferred form of the switchcomprises a housing 12 consisting of two Subframes 14 and 16 each havingfour bolt holes such as 18, the sub-frames being bolted together bybolts 20. The bolt holes form a square so that the hub-frames can bebolted together in any one of four ways depending on the desireddirection of bus access as will become evident from the followingdescription. Each sub-frame comprises four walls 22 of electricallyinsulating material of any desired type such as laminates impregnatedwith phenolic resins or the like, the walls 22 being screwed together byscrews 24. It will be apparent that this is only an illustrative form ofconstruction, and the sub-frames as well as the frame itself may bebuilt up in any other desired and suitable manner.

The joined sides of the sub-frames each have large circular openings 26,and the opposite walls have smaller openings which form bearings 28 forthe shaft ends of a rotor 30. The rotor is of built-up construction andcomprises a pair of identical electrical conductors 32 and 34 and aninsulating body 36. The parts 32, 34 and 36, when fitted together, formcylinder which extends substantially the full distance between the endbearings 28 within the sub-frames. There is a clearance between thecylinder and the openings 26. Screws 38 are received in radialcountersunk holes in the conductors 32 and 34, and are threaded into theinsulator 36. These screws are alternated axially of the rotor toprevent electrical connection of the conductors through the screws.Preferably, the conductors 32 and 34 have flat longitudinal groovesadjacent the insulator 36 and pieces of insulation 46 are received inthese grooves,

thus increasing the insulation between the ends of the screws 38 and theconductors.

The insulator 36 also preferably has longitudinal slots 42 extendingradially inward from the surface, thereby adding substantial length tothe surface path between the two conductors. This minimizes thepossibility of leakage current tiowing over the surface of the insulator36 between the conductors.

The insulator 36 has integral shaft extensions 44 and 46 slidablyfitting within the bearings 2S. As shown, these extensions comprisefragmentary cylinders with opposed flat surfaces separated by thethickness of the insulator 36, but it is obvious that the shaftextensions can be built up or cast to form fully cylindrical bearingsurfaces. Also, while simple sleeves bearings have been shown, it isobvious that thrust bearings and other' types of bearings may beemployed. It will be noted that in the preferred form, both the shaftextensions 44 and 46 and the end walls 22 of the sub-frames are made ofinsulating material. The mechanical load on the bearings, as willhereinafter appear, is balanced so as to reduce wear on the slidingsurfaces. The shaft extension 46 is suiiiciently long to receive anoperating arm 48 which is secured thereto by screws 50. The arm 48 has abearing 52 to receive a pin for a clevis connection to a suitableoperating crank. This crank may be operated manually or automaticallywith the aid of pneumatic, hydraulic or electrical power.

Two pairs of bus bars 54 and 56 are respectively received into open endsof the sub-frames 14 and 16, and secured to the side walls 22 by meansof screws 58. As shown in FIG. 2, the bus bars extend to positionsadjacent but not touching the surface of the rotor 30. Ordinarily, thesebars are formed of copper and plated with silver, and are designed tocarry considerable currents. The bars 56 may comprise the inputconnections and the bars 54 may comprises the output connections, orVice versa, the illustrated form of the invention falling into thegeneric class of double-pole, double-throw switches connected forcurrent reversal.

Connections from the bus bars to the rotor are accomplished by a numberof silver plated at copper contacts such as 60a, each sub-frame havingtwo rows of such contacts. Springs 62 under compression urge theindividual contacts against the bus bars and the rotor.

The self-aligning, tull-oating and independent support for the contactsis described as follows. A channel bracket 64 has a number oflongitudinally spaced holes, two in the illustrated case, into which arereceived the reduced ends of threaded adjustment screws 66, the screws66 being threaded into bushings 68 fitted in the walls of each subframe.The compression springs 62 bear upon the bracket, thereby causing it toconform to the screw adjutrnents at spaced locations along its length.This prevents the bracket from bowing outwardly under the vdistributedspring pressure, and ensures that the springs will be equally compressedand produce substantially equal pressure on all contacts.

Received with in each spring 62 is a tab 69 of a at spacer element 70having holes for receiving guide rods 72 and 74. These rods tit in blindholes 76 (FIG. 1) in the walls of the sub-frames, and also pass throughenlarged holes 78 and 80 in the contacts 60. Each spring 62 bears upon aslightly recessed edge 82 of each of two adjacent contacts, whereby thecontacts are continuously urged against the rotor and a bus bar 56.Intermediate spacer plates 83 shaped like the elements 70 but withoutthe tabs 69 are used to complete a loose assembly which restrains thesprings and contacts while at the sarne time permitting them to moveindependently.

The contacts in each sub-frame are diametrcally opposed, and in the formof FIGS. l and 2 the contact pairs in one sub-frame are angularlydisplaced by 90 degrees in relation to those of the other sub-frame.

Both current reversal and current breaking functions are provided. Forexample, if a source of direct current is connected between the bus bars56 which are in turn connected with contacts 60a and tlb (FIG. 2), thissource may be connected across the bus bars 54 through the contacts 60Cand 60d by turning the rotor 30 in either direction from the positionshown in FIG. 2 through a suiiicient angle to bring the contacts 60a and60b into connection with conductors 32 and 34. Rotation in one directionproduces one polarity at the output bus bars, and rotation in the otherdirection produces the opposite polarity.

Because of the large currents ordinarily carried by this type of switch,it is common to connect it in series with a current-breaking switch thatis opened whenever a current reversal is required. However, it isobvious that the present invention can also be used for current breakingwhere arcing and the attendant pitting of the rotor and contacts presentno serious problem.

FIGS. 4 and 5 show how the rotor may be designed to permit the input andoutput bus bars to enter the switch from different directions than thoseof FIG. 3. Conductors 84 and 86 are separated by insulation 88, and eachconductor has a part in each of two sections and 92 respectivelysituated within the sub-frames 14 and 16, the parts being angularlydisplaced in relation to one another by 90 degrees. There is also amid-section 94 of larger diameter, whereby additional metal is added tothe cross-section of each conductor where the parts of the two sections90 and 92 are connected, reducing the resistance of the current path atthis cross-section.

With the rotor of FIG. 4 the sub-frames 14 and 16 are bolted together inthe positions shown in FIG. 5, with the result that the input contacts56 and output contacts 54 are brought into the switch from the sameside.

It will be evident from the foregoing description that with the use ofthe rotor 30 of FIGS. 1 and 2 or the rotor 83 of FIG. 4, the input andoutput bus bars may be arranged to enter the switch from any one of fourdifferent directions, 4making a total of 16 possible arrangements ofthese connections.

Also, it is obvious that still other arrangements can be devised whereinthe displacement between the two parts of each conductor in the rotorcan be some angle other than zero degrees or 90 degrees. Also, there canbe more than two conductors on the rotor, all mutually separated bybodies of insulation. In such case, there would be an equal number ofrows of contacts within each sub-frame, and these contacts would bedistributed angularly about the rotor. For example, with threeconductors there would be three rows of contacts 60 angularly displacedat 120 degrees.

It will be apparent that various techniques may be employed for coolingthe switch. For this purpose the subframes can be suitably modified toretain oil, or the entire assembled switch may be contained within asuitable enclosure iilled with the cooling fluid. Much of the heat isgenerated by the contact resistance and results in raising thetemperature of the rotor. If necessary, the conductors of the rotor canbe hollow, with or without their internal surfaces being adapted asheat-exchange tins. Also, it is possible to circulate the cooling iiuidaround the rotor since the sub-frames have open sides.

The application of the switch in either direct current or alternatingcurrent circuits will be apparent, and alternating current applicationsmay include a plurality of phases. Also, there may be several suchswitches ganged together on a common shaft.

While the invention has been described with reference to a preferredembodiment, it will be apparent to those skilled in the art that othervariations in structure and arrangements of the parts can beaccomplished without departing from the spirit or scope of thisinvention.

Having thus described the invention, I claim:

l. A high current switch having, in combination,

a housing comprising a pair of sub-frames each having provision forconnection to a pair of external conductors,

a rotor rotatable in the housing and having a pair of elect-ricalconductors and insulation therebetween forming two coaxial,longitudinally displaced sections, one section within each sub-frame,the sections each including a part of one of the conductors forrnc ing asubstantial portion of a solid cylinder.

means for interconnecting the sub-frame in a plurality of mutualorientations angularly displaced about the axis of the rotor, and

a pair of pressure contacts for each section supported by thecorresponding sub-frame and resiliently urged into contact with thesurface of said section, both contacts of one pair being in position totouch the insulation when the contacts of the other pair are each inposition to touch a separate conductor.

2. The combination according to claim 1, in which the electricalconductors are of generally semicylindrical shape.

3. The combination according to claim 1, in which one pair of pressurecontacts is angularly and longitudinally displaced from the other pair.

4. The combination according to claim 1, in which one pair of pressurecontacts is longitudinally but not angularly displaced from the otherpair.

5. The combination according to claim 1, with means to turn the rotorbetween two positions wherein the connections between one pair ofcontacts and the other are respectively reversed.

6. The combination according to claim l, in which the rotor is supportedon an insulating shaft. 5 7. The combination according to claim 1, inwhich the surfaces of each conductor in the two sections are relativelydisplaced at right angles about the axis of the rotor. 8. Thecombination according to claim l, in which the provision for connectionto a pair of external conductors comprises a pair of bus bars secured toeach sub-frame, each pressure Contact bearing on a bus bar.

9. The combination according to claim 8, and spring means resilientlyurging each contact against a bus bar and the rotor.

References Cited UNITED STATES PATENTS 1,146,204 6/1915 Pearce 200-15520 FOREIGN PATENTS 266,811 3/1927 Great Britain. 709,290 5/1954 GreatBritain. 722,941 2/ 1955 Great Britain.

25 ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

